The present invention relates to a circuit arrangement for driving a saw-tooth current, having a trace and retrace interval, in a coil, in particular, a deflection coil of a television cathode ray tube.
A circuit arrangement of this kind is described by A. Farina and G. Zappala in an article entitled "Self-stabilized horizontal deflection circuit", published in the 1976 n.6 issue of the "Elettronica e Telecomunicazioni" magazine, pages 237-241.
The arrangement comprises a retrace capacitor and a trace capacitor connected to the coil so as to form a deflection circuit which oscillates freely during the retrace interval, a first diode connected in parallel with the deflection circuit and having such polarity as to be made conductive by the saw-tooth current flowing through the coil during the first part of the trace interval, a second diode connected in parallel with the deflection circuit and having such polarity as to be made conductive by the saw-tooth current during the second part of the trace interval, a controllable switch having a control electrode, connectable to a periodic control signal source so as to be rendered conductive during part of the trace interval, and connected via a first inductor to a supply source such that, during the part of the said trace interval in which the said switch is conductive, energy is stored in the said first inductor, and means for transferring the energy stored in the first inductor partly to the said deflection circuit, via a third diode and partly to a further capacitor during the part of the interval in which the said switch is not conductive.
The circuit described in this article dissipates part of the energy picked up by a relatively high voltage supply source (220 V) in a relatively low voltage auxiliary load circuit (12 and 24 V).